The Truth About Crunches: Why They’re Overrated for Core Strength
If you’ve ever wanted stronger abs, chances are you’ve done your fair share of crunches, sit-ups, and maybe even some leg raises. They burn, they’re simple to do, and they feel like they should work. But if you’re trying to build real core strength and stability—the kind that prevents injuries, improves posture, and enhances athletic performance—these classic exercises might not be your best bet.
What Does “Core Strength” Actually Mean?
Before we dig into why crunches fall short, let’s clarify what core strength really is. Your core isn’t just your abs; it’s a complex system of muscles including the rectus abdominis (the “six-pack” muscle), transverse abdominis, obliques, diaphragm, pelvic floor, and deeper stabilizing muscles like the multifidus (McGill, 2010). These muscles work together to create stability—not just flexion (bending forward), which is all crunches train.
True core strength means resisting movement (anti-extension, anti-rotation, anti-lateral flexion) to protect your spine and transfer force effectively through your body. This is critical for everything from lifting weights to running efficiently.
Crunches and Sit-Ups: Why They Miss the Mark
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They Reinforce a Dysfunctional Movement Pattern
Crunches and sit-ups train spinal flexion (bending forward), but your core’s primary role is to resist unwanted movement, not create excessive motion (McGill, 2014). The constant flexion can reinforce poor posture and even contribute to lower back pain, especially for those who already spend too much time sitting. -
They Don’t Engage the Deep Core Muscles Effectively
Crunches primarily target the rectus abdominis (the six-pack muscle) but largely ignore the deeper transverse abdominis—a key stabilizer that wraps around your spine like a built-in weight belt. Research suggests that exercises emphasizing isometric contraction and whole-body integration (like planks, dead bugs, and farmer’s carries) do a far better job at activating these muscles (Behm et al., 2010). -
They Put Unnecessary Strain on the Spine
Studies have shown that excessive spinal flexion under load (like repeatedly doing sit-ups) can increase disc pressure and contribute to spinal issues over time (Callaghan & McGill, 2001). Think about it: our spines aren’t meant to flex back and forth thousands of times under strain—it’s not a natural or necessary movement for functional strength. -
They Don’t Translate Well to Real-World Strength
When in daily life do you find yourself lying on your back, curling your upper body forward? Almost never. Real-world strength is about controlling movement in multiple planes, resisting forces, and stabilizing under load—something crunches don’t train effectively.
What to Do Instead: Smarter Core Training
If you want true core strength, focus on anti-movement exercises and compound lifts that integrate core engagement naturally. Here are some of the best alternatives:
✅ Planks (and Their Variations) – Great for anti-extension, forcing your core to resist sagging and maintain spinal neutrality.
✅ Dead Bugs & Bird Dogs – Train coordination and lumbo-pelvic stability while strengthening the deep core.
✅ Pallof Presses – One of the best exercises for anti-rotation, teaching your core to resist twisting forces.
✅ Loaded Carries (Farmer’s, Suitcase, Overhead) – Develop total-body stability and endurance by forcing your core to work dynamically under load.
✅ Squats & Deadlifts – These aren’t just leg exercises! When done correctly, they demand high levels of core engagement to maintain proper posture and stability.
The Takeaway
If your goal is to develop a stronger, more stable core, it’s time to ditch the endless crunches and sit-ups in favor of exercises that mimic how your core is actually meant to function. Focus on stability, resistance to movement, and integration with full-body exercises, and you’ll build a core that not only looks strong but actually is strong.
References:
- Behm, D. G., Drinkwater, E. J., Willardson, J. M., & Cowley, P. M. (2010). The use of instability to train the core musculature. Strength & Conditioning Journal, 32(3), 33-46.
- Callaghan, J. P., & McGill, S. M. (2001). Low back joint loading and kinematics during standing and unsupported sitting. Ergonomics, 44(3), 280-294.
- McGill, S. M. (2010). Ultimate Back Fitness and Performance. Backfitpro Inc.
- McGill, S. M. (2014). Back Mechanic: The Secrets to a Healthy Spine Your Doctor Isn’t Telling You. Backfitpro Inc.